Spark-plug



E. M. JOHNSON.

SPARK PLUG. A-Pmiclvnon.A mso mz. 5. 19.19.

Patentd May 25, 1920.

. M. fonson PATENT OFFICE.

EDWARD M. JOHNSON, 0F BLYTHEVILLE, ARKANSAS.I

SPARK-PLUG.

Specification o f Letters Patent.

` Patented May 25, 1920.

Application led April 5, 1919. Serial No. 287,759.

To all whom t may concern.'

Be it known that I, EDWARD M. JOHNSON, a citizen of the United States, residing at Blytheville, in the county of Mississippi and State of Arkansas, have invented certaln new and useful Improvements in Spark- Plugs, of which the following is a specification, reference being had to the accompanyin drawings. p

'hisvinvention relates to certain improvements in spark plugs and is an improvement on the structure disclosed in my co-pending application, Serial. No. 273,347, filed January 27, 1919, and it is an object of the invention to provide novel and improved means for maintainin the primary electrode in assembled position relative to the body o r shell, together with means whereby said primary electrode may be conveniently adjusted with respect to the secondary electrode.

Another object lof the invention is to provide a novel and improved device of this general character which may be assembled.

with convenience and facility and in a manner to substantially eliminate all possibility of breakage.

The invention consists in the details of construction and in the combination and arrangement .of the several parts of my improved spark plug whereby certain important advantages are attained andi the device rendered simpler, less expensive and otherwise more convenient and advantageous for use, as will be hereinafter more fully set forth.

The novel features of my invention will hereinafter be definitely claimed.

In order thatv my invention may be the better understood, I will now proceed to describe the same with reference to the accompanying drawings, wherein:

Figure 1 is a longitudinal sectional view taken through a spark plug constructed in accordance with an `embodiment of my invention, with the electrodes in elevation, and

Fig..2 is a transverse sectional view taken through the central portion of my improved plug as herein embodied.`

As disclosed' in the accompanying drawings, B denotes a body or shell formed of conductive material, preferably brass, and which has an end portion 1 threaded where `by the device may be properly applied in Workin position. The central portion 2 of the bo y or shell B is angular 1n cross section so that the same may have engaged therewith a suitable tool either for applying or removing the plu The body or shelld has disposed axiallyHM lfor a purpose to be hereinafter referred to.

Arranged within the bore 3 is a sleeve 5 of vinsulating material and of a length in excess of the len th of the body or shell B. The sleeve 5 is ofg a major diameter less than the diameter of the bore 3 so that when the sleeve 5 is applied Within the body or shell B, said sleeve is substantially surrounded by an air space a in communication with the atmosphere through the ports 6 formed lin the body or shell Band preferably diametrically opposed. By this it will be seen that there will be a constant flow of air through the ports 6 and around the sleeve 5 to effectually cool the primary electrode'7 slidably disposed through. but snugly fitting within the sleeve 5.

The opposite end portions of the primary electrode 7 are threaded, as indicated at 8 and 8, and the threaded portion 8 at the firing end of the electrode 7 has engaged `therewith the cup-like member 9 having its side wall or flange 10 inwardly directed and lcontacting with the washers 11 of mica or other insulating material seated within the recess or rabbet 4 hereinbefore referred to.-

hereinafter referred to, will be imposed directly upon the body or shell B.

The washers 1l snugly surround an eX- tension 12 at the axial center of the sleeve l 5 at the firing end of the plug, and the body or main portion of the member 9 directly contacts with the outer end of said'extension. As is clearly illustrated in Fig. 1, the extension 12 is of a diameter materially less than the diameter of the sleeve 5 proper.

The opposite end portion of the sleeve 5 extends outwardly of the outer end of the body or shell B and surrounding said extended portion of the sleeve 5 and Contactin with the adjacent end of the body or shel B is a washer 14 of insulating material.

i The electrode 7 extends beyond the extended end portion of the sleeve 5 and engaged with said extended or threadedportion 8a is a clamping nut 15. The nut 15 v engages a washer 16 surrounding the electrode 7 and contacting with the adjacent end of the sleeve 5. The washer 16 is off-a diameter in excess of the sleeve 5 and interposed betweenthe washers 14 and 16 and loosely surrounding the extended portion of the sleeve 5 is a sleeve 17 of insulating material.

Also threaded upon the portion 8a of the electrode 7 is a binding nut or member 18 coaeting with the nut 15 hereinbefore referred to.v

The working or firing end of the body or shell B at one side of the bore 3 has in threaded engagement therewith an end portion of a secondary electrode 19 which coacts with the firing or working end of the primary electrode 7 in a well known manner.

By proper adjustment of the member 9 and the nuts 15 and 18, the primary electrode 7 may be adjusted longitudinally through the sleeve 5 in order to provide a desired gap relative to the secondary electrode 19.

It is also to be particularly noted that the member 9 and the nut 15 coact with the primary electrode 7 and with the sleeve 5 in a manner to effectively maintain the sleeve 5 and the primary electrode 7 in assembled relation. v.

It will also be obvious that the yparticular manner of'assemblage as herein embodied readily permits a replacement of any of the parts,'and it will also be self-evident that the liability of fouling the firing end of the plug is substantial-ly eliminated.

From the foregoing description, it is 'thought to be obvious that a spark plug constructed in accordance ,with my invention is particularly well adapted for use by reason of the convenience and facility with which it may be assembled and operated,

and it will also b'e obvious that my invention is susceptible of some change and modiication without departing from the principles and spirit thereof and for this reason I do not wish to be understood as limiting myself to the precise arrangement and formation of the several parts herein shown in carrying outl my invention in practice except as hereinafter claimed.

I claim:

A spark plug comprising a shell having a bore extending therethrough, an insulating sleeve extending through the bore and of a length to extend beyond the shell, a primary electrode disposed through the sleeve and extending beyond opposite ends thereof, clamping members threaded upon the opposite end portions ofthe primary electrode and coacting with the sleeve and the shell for maintaining the primary electrode and sleeve in assembled position relative to the shell, the sleeve at the ring end of the plug being provided with an extension, the bore of the plug at the firing end being enlarged, an insulating washer surrounding the extension of the sleeve and fitting within the enlarged portion of the bore, the member coactlng with the firing end of the plug being vcup-like and having its side flange inwardly directed and contacting directly with the washer, said member being of a diameter whereby said flange contacts with thewasher outwardly of the bore of the shell, and a secondary-electrode carried by the shell and coacting with the primary electrode.

In testimony whereof I hereunto afiix my signature in the presence of two witnesses.

EDWARD M. JOHNSON.

Witnesses:

W. O. ANTHONY, J. K. SoR'rAm. 

